Posts tagged “Glaucomys volans”

With most deciduous trees having lost their leaves, squirrel nests, or dreys, are more noticeable. Red Squirrels, Eastern Gray Squirrels and Flying Squirrels all build dreys. Those of the Red Squirrel are round, grassy balls, 8” – 10” in diameter. In contrast, Gray Squirrel nests are usually larger and made of sticks and leaves. Flying Squirrel dreys are so high that they are rarely observed.

The dreys most commonly seen are made by Gray Squirrels. Usually 30 or more feet high, these shelters are typically built near the main trunk of the tree, in a crotch where several small branches meet, or on a strong, thick limb. Construction takes place in the summer or early fall, before trees have formed the abcission layers that cause leaves to separate and fall from branches. Therefore, the leaves on a drey’s branches tend to remain for quite some time, forming an effective water-shedding outer layer.

Branches are loosely woven into a foot-wide hollow sphere. The drey is lined with insulating grass, moss, leaves, and shredded bark. Usually there is one entrance/exit hole, facing the trunk (so as to keep rain out). Often squirrels build two dreys, giving themselves another shelter option should one nest be disturbed by a predator or overrun with parasites.

A drey is usually inhabited by one squirrel, but two are known to occupy a single drey in order to keep warm in the winter. Gray Squirrels give birth in late winter and again in the summer. A more protective tree cavity usually serves as a nursery in the winter, and the drey in summer. The average drey is only used for a year or two before it is abandoned.

If you feed birds, you might want to glance at your feeders on your way to bed at night. With luck, you may encounter a Northern or Southern Flying Squirrel, or a swinging feeder indicating the recent departure of one. These nocturnal rodents remain active all year and often take advantage of the ample supply of food that bird feeders provide. Flying squirrels often refurbish abandoned tree cavity nests of birds and squirrels for winter use. During very cold weather they stay in these nests for prolonged periods, often huddling with several other flying squirrels. The relative warmth of this winter means the chances of seeing a “flying” night visitor at your feeder are greatly increased.

Are you finding that the amount of seed in your bird feeders drops precipitously after dark? Those of us in black bear country are advised to bring feeders in at night so as not to attract bears, but occasionally several hours of darkness have passed before I remember to do so. When that happens, the feeders inevitably need filling. What stealthy critter is visiting once the sun goes down? Very possibly, flying squirrels are the culprits. These nocturnal rodents can glide as far as 295 feet from tree to tree, or tree to ground. They stretch their legs out and direct their glide by controlling the position of the flap of skin (patagium) that extends from the outside of the wrist on the front leg to the ankle of the hind leg on both sides of their body. Their broad, flattened tail acts as a parachute, rudder, stabilizer and brake during the glide. Feeders are rarely far enough from a tree to necessitate a glide – a short leap does the trick. If you feed birds, try shining a light on your feeders after the sun goes down. You may very well be treated to the sight of several flying squirrels helping themselves to your sunflower seeds and suet.

During the winter flying squirrels often huddle together in large communal nests, sometimes with populations numbering over two dozen squirrels, in an effort to keep warm. Two years ago 22 of these nocturnal creatures spent the majority of the winter in my log cabin, doing just that. Although flying squirrels do not hibernate, if temperatures become too severe the squirrels will enter a state of torpor until temperatures return to normal.

We have two species of flying squirrels in most of New England, the Southern (Glaucomys volans) and Northern (Glaucomys sabrinus), which is larger and usually more brownish than its cousin. One could deduce that these gentle rodents are nocturnal just by looking at the size of their luminous eyes. Because they feed at night, we don’t set eyes on them very often, except for an occasional lucky glance at the bird feeder before heading to bed. If we did observe them more often, we would marvel at their stretching their legs out, extending a flap of skin that runs from their front legs to their hind legs, and effortlessly soaring from one tree to another — as far as 150 feet horizontally from a height of 60 feet. One documented sighting that I would love to observe is a female carrying young while gliding!